When empty the flashbag is small, like a sack, and then it balloons up as stuff is added, alerting the owner that it’s time to get another one or shift some stuff. What isn’t quite clear is what happens when it’s full. The blurb suggests a violent end:

When the device is about to blow up you will see the familiar error message on your screen: “There is not enough free space”.

I think the author, designer Dima Komissarov, may not quite mean that, although it does have interesting implications for data storage. People might be a bit more careful with what they load onto their storage devices if excessive downloading brings the risk of explosion. Might be worth honing the concept before it hits the shelves.